Pneumatic valve

ABSTRACT

A fluid bladder valve for a pneumatic vehicle seat adjustment device is disclosed. The valve comprises a first chamber configured to be connected to a fluid source, a second chamber configured to be connected to the fluid bladder, a third chamber configured to be connected to an environment, a fourth chamber connected to the first chamber via a first fluid passage, connected to the second chamber via a second fluid passage, and connected to the third chamber via a third fluid passage; and an actuator comprising a membrane disposed in the fourth chamber and an actuator element disposed in the third chamber and coupled to the membrane and configured to move the membrane between a first position wherein the first fluid passage is opened and the third fluid passage is closed, and a second position wherein the first fluid passage is closed and the third fluid passage is opened.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments are explained in more detail hereunder withreference to the appended drawings. In the drawings:

FIG. 1 shows a schematic view of an exemplary pneumatic valve accordingto the disclosure which in an exemplary manner is used in an adjustmentdevice for adjusting a contour of a seat bearing surface of a vehicleseat, wherein FIG. 1 shows a membrane element of the pneumatic valve ina first position;

FIG. 2 shows a schematic view of an exemplary pneumatic valve accordingto the disclosure, wherein FIG. 2 shows the membrane element in a secondposition;

FIG. 3 shows a schematic detailed view of a fragment of a furtherembodiment of an exemplary pneumatic valve according to the disclosure,wherein a membrane element of the pneumatic valve is shown in a firstposition;

FIG. 4 shows a schematic detailed view of the exemplary embodiment ofFIG. 3 , having the membrane element in the second position;

FIG. 5 shows a schematic view of an exemplary valve assembly accordingto the disclosure;

FIG. 6 shows a schematic sectional view of the exemplary valve assemblyalong the line I-I of FIG. 5 ;

FIG. 7 shows a schematic view of a further exemplary valve assemblyaccording to the disclosure, wherein FIG. 7 shows the valve assembly ina first switched position;

FIG. 8 shows a schematic view of the exemplary valve assembly of FIG. 7, wherein FIG. 8 shows the valve assembly in a second switched position;and

FIG. 9 shows a schematic view of the exemplary valve assembly of FIG. 7, wherein FIG. 9 shows the valve assembly in a third switched position;

DETAILED DESCRIPTION

The present disclosure relates to a pneumatic valve, and, in particular,for a fluid bladder of a pneumatic adjustment device of a vehicle seat.The present disclosure furthermore relates to a valve assemblycomprising a valve of this type, as well as to an adjustment devicecomprising a valve of this type.

Pneumatic valves are used for controlling fluid flows in a multitude oftechnical fields of application. Pneumatic valves of this type are to befound, for example, in a pneumatic adjustment device for adjusting aseat surface or seat rest, respectively, (collectively referred to as aseat bearing surface) of a vehicle seat. The adjustment device in aregion of the seat bearing surface usually comprises one or a pluralityof fluid chambers or fluid bladders, respectively, which can be filledwith a fluid, in particular with compressed air. By filling a respectivefluid bladder with fluid the volume of said fluid bladder is enlarged,on account of which the properties of the seat bearing surface can bemodified and thus a contour of the seat bearing surface can be adapted.In order for the fluid bladders to be filled with fluid, the fluid isfirst generated by a fluid source such as a fluid compressor andsubsequently routed via one or a plurality of pneumatic valves to arespective fluid bladder.

It is known herein for so-called valve actuators to be used foractivating such valves. Said valve actuators are configured foractivating a membrane element of the valve such that a fluid connectorof the valve can be opened and/or closed.

In the case of a first group of known pneumatic valves, valve actuatorsof this type are disposed in the valve in such a manner that there is acomplete fluidic separation between the fluid and the valve actuator.This complete separation can be achieved, for example, by a fluid-tightseparating layer between the membrane element and the valve actuator.However, the additionally required actuating force of the valve actuatorherein is disadvantageous since not only the membrane element has to bemoved but also the fluid-tight separating layer.

In the case of a second group of known pneumatic valves, the valveactuator is disposed within the valve space that is passed through bythe flow of fluid, in particular within the valve space that isconnected to the fluid source. In the case of this group of pneumaticvalves, no additional actuating force of the valve actuator is indeedrequired. However, it is disadvantageous that the valve actuators haveto be fluidically sealed in relation to the environment. This leads toadditional costs and to an increased complexity in terms of theconstruction of the valve.

It is therefore an object of the present disclosure to provide acost-effective pneumatic valve in which the valve actuator has to handlecomparatively minor actuating forces and additional sealing elements inthe region of the valve actuator can at the same time be dispensed with.

Said object is achieved by the subject matter of the independent claims.Advantageous configurations are the subject matter of the dependentclaims.

According to a first aspect, a pneumatic valve for a fluid bladder of apneumatic adjustment device of a vehicle seat is provided. The pneumaticvalve comprises a first valve chamber which is connectable to a fluidsource, a separate second valve chamber which is separate from the firstvalve chamber and is connectable to the fluid bladder, and a separatethird valve chamber which is separate from the first valve chamber andthe second valve chamber and is connectable or connected to anenvironment of the pneumatic valve. The term “environment” herein refersto that region of the pneumatic valve that is disposed outside the valveand is at ambient pressure. In other words, the environment of the valveis the atmosphere surrounding the valve, and in particular is not thefluid bladder or the fluid source. Besides the first, the second, andthe third valve chamber, the pneumatic valve according to the disclosurefurthermore comprises a separate fourth valve chamber which is separatefrom the first valve chamber, the second valve chamber, and the thirdvalve chamber. The fourth valve chamber herein is fluidically connectedonly via a first fluid passage to the first valve chamber, only via asecond fluid passage to the second valve chamber, and only via a thirdfluid passage to the third valve chamber.

The pneumatic valve according to the disclosure furthermore comprises anactuator unit which comprises a membrane element disposed in the fourthvalve chamber and an actuator element which is disposed in the thirdvalve chamber and is coupled to the membrane element and is configuredfor moving the membrane element between a first position in which thefirst fluid passage is opened and the third fluid passage is closed, anda second position in which the first fluid passage is closed and thethird fluid passage is opened. In other words, the second fluid passageis at all times opened, in both the first position as well as in thesecond position of the membrane element.

On account thereof, fluid in the first position of the membrane elementcan flow exclusively from the first valve chamber (via the fourth valvechamber) into the second valve chamber while the third fluid passage isclosed by the membrane element such that there is no fluidic connectionbetween the first valve chamber and the third valve chamber. It isprevented on account of this arrangement that fluid in the firstposition of the membrane element can flow from the fluid source to thethird valve chamber. However, since the actuator element is disposed inthe third valve chamber it is not necessary for the actuator element tobe disposed in a fluid-tight manner in the third valve chamber. Onaccount thereof, components which serve for sealing the actuator elementcan be saved, on account of which the complexity in terms ofconstruction of the valve and the production costs can be reduced.

At the same time, the first fluid passage is closed and the third fluidpassage is opened in the second position of the membrane element. Thefluid in the second position of the membrane element can therefore flowexclusively from the second fluid chamber into the third fluid chamberwhile a fluidic connection between the second valve chamber and thefirst valve chamber is blocked. Since the fluid bladder is ventilated oremptied, respectively, in the second position of the membrane element,that is to say that the fluid is to be fed to the environment anyway, itis again not necessary for the actuator element to be disposed in afluid-tight manner in the third valve chamber.

Furthermore, since the actuator element is disposed in the third valvechamber and the membrane element is disposed in the fourth valvechamber, and the membrane element in the first position as well as inthe second position prevents any fluidic connection between the firstvalve chamber and the third valve chamber, it is not necessary for afluid-tight separating layer or the like to be provided between theactuator element and the membrane element. An unnecessary increase inthe actuating forces of the actuator element is prevented on accountthereof. In addition, the membrane element, which is preferablyconfigured as a thin film, can be moved by the actuator element with acomparatively minor actuating force. On account thereof a cost-effectivepneumatic valve is provided which is simple in terms of construction andin which neither the actuating force of the actuator element isunnecessarily increased nor complex sealing elements are required in theregion of the actuator element.

According to one design embodiment of the pneumatic valve, the actuatorelement is a shape memory alloy element (SMA element) which, forexample, is composed of a binary or ternary NiTi-based alloy and whenimpinged with electric energy is configured for activating the membraneelement. In this design embodiment, the actuator element is configuredas a shape memory alloy element which is heated by impingement withelectric energy, in particular electric current, and the energy inputassociated therewith, on account of which the shape memory alloy elementis deformed, in particular modifies the length thereof, and aftersubsequent cooling reassumes the original shape thereof. The pneumaticvalve can be further simplified on account of this design embodimentsince the shape memory alloy element, as opposed to other actuatorelements such as, for example, a piezoelectric or magnetic actuatorelement, is of a significantly simpler construction. For example, theshape memory alloy element is electrically connected to a circuit boardwhich is configured for impinging the shape memory alloy element withelectric energy. However, since the shape memory alloy element isdisposed in the third valve chamber and no particular precautionspertaining to fluid tightness are required, the circuit board canreadily be inserted in an opening of the third valve chamber, forexample, wherein a fluidic connection between the third valve chamberand the environment of the valve can continue to exist even in the caseof an inserted circuit board. No additional requirements pertaining tothe fluid-tight fastening of the circuit board thus have to be set inthis design embodiment, on account of which costs for contacting thecircuit board can also be saved.

According to one further design embodiment of the pneumatic valve, themembrane element comprises a first sealing portion for fluidicallysealing the first fluid passage, and a second sealing portion forfluidically sealing the third fluid passage, and the membrane element inthe region of the first sealing portion and/or in the region of thesecond sealing portion comprises a mechanical reinforcement portion forreinforcing the membrane element in mechanical terms. The mechanicalreinforcement portion increases the stability of the membrane element inthe region of the first and/or the second sealing portion, respectively,on account of which the service life of the pneumatic valve can beincreased.

According to one further design embodiment, the membrane element definesa passage opening which in the second position of the membrane elementis configured for fluidically connecting the third fluid passage to thesecond fluid passage. The passage opening thus represents a fluidicconnection between the second fluid passage, which for example isfluidically connected to the fluid bladder, and the third fluid passage,which for example is fluidically connected to the environment of thevalve. On account thereof, the fluid bladder can be emptied in theenvironment via the passage opening.

In one particularly advantageous design embodiment, a fluid passage areaof the passage opening is at least as large as a fluid passage area ofthe third fluid passage. It is achieved on account thereof that anideally small differential pressure between the upper side and the lowerside of the membrane element prevails on the membrane element. Anideally small differential pressure is advantageous since, on accountthereof, a (differential pressure) force acting on the membrane elementcan be minimized. This results in the force acting from the membraneelement on the actuator element is also minimized such that theactuating force to be provided by the actuator element is notunnecessarily increased. Of course, it is also possible for the membraneelement to define a plurality of passage openings. In this case, thepassage openings are chosen such that an overall fluid passage areathrough the plurality of passage openings is at least as large as thefluid passage area of the third fluid passage.

According to one further design embodiment of the pneumatic valve, theactuator unit comprises a coupling element which couples the blockingelement to the actuator element. This design embodiment is particularlysimple in terms of construction and is therefore cost-effective. It isparticularly advantageous for the coupling element to be movablymounted, for example, and to be moved only by an activation withpressure by the actuator element or by an activation with pressure bythe membrane element.

According to one preferred design embodiment, the coupling elementextends through the third fluid passage. On account thereof, thecoupling between the actuator element and the membrane element becomeseven simpler.

According to one particularly preferred design embodiment, the couplingelement is a tappet which is molded to the membrane element and whichfrom the membrane element extends in the direction toward the actuatorelement. The tappet in this design embodiment is configured so as to beintegral to the membrane element and can be produced conjointly with themembrane element as an integral element, for example by extrusion.

According to one further design embodiment the membrane element isshaped in such a manner that the membrane element is pretensioned to thefirst position or to the second position. On account thereof, arestoring element for pretensioning the membrane element can bedispensed with.

According to one further design embodiment, the fourth valve chamber isformed by a pot-shaped base element and a cover element that covers thebase element, and the membrane element comprises a clamping portionwhich is configured for clamping the membrane element between the baseelement and the cover element. The clamping portion can furthermore sealin an air-tight manner the gap between the base element and the coverelement. In this design embodiment the membrane element can beintegrated in the fourth valve chamber in a simple manner in terms ofconstruction.

According to one preferred design embodiment, the clamping portioncomprises a material thickening which is configured for reinforcing themembrane element in mechanical terms and/or equalizing tolerancesbetween the base element and the cover element.

According to one further design embodiment, the actuator unitfurthermore comprises a lever element which is disposed in the thirdvalve chamber and via a linking region is connected to a housing of thepneumatic valve and/or a wall of the third valve chamber. A firstfastening portion of the lever element herein is connected to theactuator element and a second fastening portion of the lever element isconnected to the coupling element such that when activating the actuatorelement a movement of the lever element is converted to a movement ofthe coupling element. It is particularly advantageous for the linkingregion to be disposed laterally between the lever element and thehousing or the wall, respectively. On account thereof, the actuatorforces of the actuator element, said actuator forces in the case of ashape memory alloy element being tensile forces, can be better received.

In one particularly preferred design embodiment, the actuator element isfastened to the first fastening portion in such a manner that a firstlever arm is formed between the first fastening portion and the linkingregion, and the coupling element is fastened to the second fasteningportion in such a manner that a second lever arm which is larger thanthe first lever arm is formed between the second fastening portion andthe linking region. In that the second lever arm is larger than thefirst lever arm, a stroke of the actuator element, or a positionalmodification of the shape memory alloy element, respectively, can beconverted to a larger stroke of the coupling element and thus to alarger stroke of the membrane element.

According to one further design embodiment, the actuator unitfurthermore comprises a restoring element which is connected to thehousing and to the lever arm and without activating the actuator elementis configured for pretensioning the membrane element to the firstposition or to the second position. On account thereof, a NO valve(normally open valve) or a NC valve (normally closed valve) can beachieved in a simple manner.

According to a second aspect, a valve assembly for two separate fluidbladders (that is to say for a first and a second fluid bladder) of anadjustment device of a vehicle seat is provided. The valve assemblycomprises a first pneumatic valve according to the first aspect, ordesigns embodiments of said first aspect, respectively, wherein thefirst pneumatic valve is configured for filling and/or emptying thefirst fluid bladder. The valve assembly furthermore comprises a secondpneumatic valve according to the first aspect, or designs embodiments ofsaid first aspect, respectively, wherein the second pneumatic valve isconfigured for filling and/or emptying the second fluid bladder.Furthermore, the first valve chamber of the first pneumatic valve isfluidically connected to the first valve chamber of the second pneumaticvalve; the first valve chamber of the first pneumatic valve and/or thefirst valve chamber of the second pneumatic valve are conjointly or ineach case fluidically connectable to the fluid source; the second valvechamber of the first pneumatic valve is connectable to the first fluidbladder; the second valve chamber of the second pneumatic valve isconnectable to the second fluid bladder; and the third valve chamber ofthe first pneumatic valve and the third valve chamber of the secondpneumatic valve are conjointly or in each case connectable or connected,respectively, to the environment. The valve assembly according to thedisclosure enables two separate fluid bladders to be filled and/oremptied in a mutually separate manner.

In other embodiments, the first valve chamber can of course be connectedto the fluid bladder instead of the fluid source, or the second valvechamber can be connected to the fluid source instead of the fluidbladder, respectively, depending on the specific application.

According to a third aspect, a valve assembly for a (single) fluidbladder of an adjustment device of a vehicle seat is provided, saidvalve assembly comprising a first pneumatic valve according to the firstaspect, or design embodiments of said first aspect, respectively, aswell as a second pneumatic valve according to the first aspect, ordesign embodiments of said first aspect, respectively. However, thesecond valve chamber of the first pneumatic valve here is fluidicallyconnected to the second valve chamber of the second pneumatic valve.Furthermore, the first valve chamber of the first pneumatic valve isconnectable to the fluid source, and the first valve chamber of thesecond pneumatic valve is connectable to the fluid bladder. Moreover,the third valve chamber of the first pneumatic valve and the third valvechamber of the second pneumatic valve are conjointly or in each caseconnectable or connected, respectively, to the environment. In thisvalve assembly, the first valve chamber of the second pneumatic valve isthus not connectable to the fluid source but to the fluid bladder. Onaccount of this conjoint switching, a valve assembly via which a fluidbladder can not only be filled and/or emptied but the pressure in theinterior of the fluid bladder can also be maintained can be achieved ina simple manner. This is particularly advantageous for a static contouradjustment of a seat bearing surface of the vehicle seat.

Of course, arbitrary other valve assemblies can be achieved by acorresponding other conjoint switching of two or a plurality ofpneumatic valves according to the disclosure, depending on the specificapplication.

According to a fourth aspect, an adjustment device for adjusting acontour of a seat bearing surface of a vehicle seat is finally provided.The adjustment device comprises a fluid bladder for adjusting thecontour of the seat bearing surface, and a pneumatic valve according tothe first aspect, or design embodiments of said first aspect,respectively, wherein the second valve chamber of the pneumatic valve isfluidically connected to the fluid bladder.

Some embodiments will be described hereunder by means of a pneumaticvalve which is used for filling and/or emptying a fluid bladder of apneumatic adjustment device of a vehicle seat. Of course, the pneumaticvalve can be used in various valve assemblies, depending on the specificapplication, and also be utilized for other purposes.

Reference is first to be made to FIG. 1 which shows a schematic view ofa pneumatic valve PV. The pneumatic valve PV in FIG. 1 is shown as partof an adjustment device VV for adjusting a contour K of a seat bearingsurface SAF of a vehicle seat FZS. The adjustment device VV comprises afluid bladder FB, in particular an elastic fluid bladder FB, which canbe filled with a pressurized fluid which is provided by a fluid sourceFQ. The volume of the fluid bladder FB is enlarged by filling thelatter, on account of which the contour K of the seat bearing surfaceSAF can be modified. The volume of the fluid bladder FB is reduced byemptying the later, such that the fluid bladder FB reassumes theoriginal shape thereof.

The pneumatic valve PV comprises a first valve chamber K1 which isconnected to the fluid source FQ. The pneumatic valve PV comprises asecond valve chamber K2 which is separate from the first valve chamberK1 and is connected to the fluid bladder FB. The first valve chamber K1and the second valve chamber K2 in the specific example of FIG. 1 areformed by a basic element BE and a base element ZE which is connected tothe basic element BE. As can be readily seen in FIG. 1 , the basicelement BE and the base element ZE form two valve chambers which arefluidically separated from one another, one of said valve chambersrepresenting the first valve chamber K1 and the other representing thesecond valve chamber K2. The first valve chamber K1 herein comprises afirst fluid connector FA1 which serves for fluidically connecting to thefluid source FQ. The second valve chamber K2 comprises a second fluidconnector FA2 which serves for fluidically connecting to the fluidbladder FB. Of course, other components may also be connected to thefluid connectors FA1, FA2.

The pneumatic valve PV furthermore comprises a third valve chamber K3which is separate from the first valve chamber K1 and the second valvechamber K2. The third valve chamber K3 in the specific example of FIG. 1is formed by the base element ZE and a cover element DE which isconnected to the base element ZE. The third valve chamber K3 isconnected to the environment of the pneumatic valve PV such that theambient pressure substantially prevails in the interior of the thirdvalve chamber K3.

The pneumatic valve PV furthermore comprises a fourth valve chamber K4which is separate from the first valve chamber K1, the second valvechamber K2, and the third valve chamber K3. The fourth valve chamber K4is composed of substantially two components.

The first component represents the base element ZE which in the regionof the fourth valve chamber K4 has a pot-shaped design comprising twoupwardly extending webs S. Said webs S enclose a region B which is opentoward the top. The second component of the fourth valve chamber K4represents a cover element AE which is placed from above onto the webs Sand delimits the region B from above. In other words, the fourth valvechamber K4 is formed by a two-part housing, the first component of saidhousing in the specific example of FIG. 1 being the base element ZE andthe second component of said housing being the cover element AE.

As can furthermore be seen in FIG. 1 , the fourth valve chamber K4 isfluidically connected to the first valve chamber K1 via a first fluidpassage FD1, and the fourth valve chamber K4 is fluidically connected tothe second valve chamber K2 via a second fluid passage FD2. In thespecific example of FIG. 1 , the first fluid passage FD1 and the secondfluid passage FD2 are configured as openings in the base element ZE,wherein the second fluid passage FD2 has a predetermined spacing fromthe first fluid passage FD1.

As can furthermore be seen in FIG. 1 , the fourth valve chamber K4 isfluidically connected to the third valve chamber K3 via a third fluidpassage FD3. The third fluid passage FD3 in the specific example of FIG.1 is configured as an opening in the cover element AE. In other words,the first fluid passage FD1 and the second fluid passage FD2 areconfigured on a first side of the fourth valve chamber K4, specificallyon the side of the base element ZE, and the third fluid passage FD3 isconfigured on a second side, opposite the first side, of the fourthvalve chamber K4, specifically on the side of the cover element AE.

As can furthermore be seen in FIG. 1 , the first fluid passage FD1extends along a first axis AX1, and the third fluid passage FD3 extendsalong a second axis AX2, wherein the second axis AX2 and the first axisAX1 are mutually coaxial, or form a common axis, respectively.

The pneumatic valve PV furthermore comprises an actuator unit A. Theactuator unit A comprises an actuator element E disposed in the thirdvalve chamber K3 and a membrane element ME which is disposed in thefourth valve chamber K4 and is mechanically coupled to the actuatorelement E and when impinged with electric energy can activate themembrane element ME such that the membrane element ME can be movedsubstantially between a first position and a second position, as will bedescribed later in more detail in the context of FIGS. 1 and 2 . Theactuator element E herein can be any arbitrary actuator element E, forexample a piezoelectric or magnetic actuator element.

The actuator element E in the specific example of FIG. 1 is a shapememory alloy element SMA, for example in the form of a wire. Shapememory alloy elements are imparted a shape modification by beingimpinged with electric energy, said shape modification being able to beutilized for activating the membrane element ME. To this end, the shapememory alloy element SMA is electrically connected to a circuit board LPwhich is likewise disposed in the third valve chamber K3.

Besides the actuator element E and the membrane element ME, the actuatorunit A comprises a coupling element KE. The coupling element KE extendsthrough the third fluid passage FD3 and couples the actuator element Eto the membrane element ME such that by impinging the actuator element Ewith electric energy the actuator element E can activate the membraneelement ME and move the latter between the first position and the secondposition. In the specific example of FIG. 1 , the coupling element KE isembodied as a separate element. This coupling element KE is moreoverlaterally guided and movable along the second axis AX2.

The actuator unit A furthermore comprises a lever element H which isconnected to the actuator element E and is connectable to the couplingelement KE. The lever element H at a linking region AB is connected tothe cover element DE and can rotate about the linking region AB. As canbe seen in FIG. 1 , the linking region AB thus is laterally between thecover element DE (which represents part of a housing of the pneumaticvalve PV) and the lever element H. This has the advantage that thetensile forces of the shape memory alloy element SMA, which actlaterally, can be better received.

The actuator element E at a first fastening portion BA1 of the leverelement H is connectable to the lever element H, and the couplingelement KE at a second fastening portion BA2 of the lever element H isconnectable to the lever element H. The first fastening portion BA1 inrelation to the linking region AB is chosen such that a first lever armHA1 is formed between the first fastening portion BA1 and the linkingregion AB. The second fastening portion BA2 in relation to the linkingregion AB is chosen such that a second lever arm HA2 which is largerthan the first lever arm HA1 is formed between the first fasteningportion BA2 and the linking region AB. On account of this designembodiment, a stroke of the actuator element E can be converted to anenlarged stroke of the coupling element KE and thus to an enlargedstroke of the membrane element ME.

The mentioned two positions of the membrane element ME are now to bediscussed in more detail hereunder.

Reference is first to be made to FIG. 1 which shows the membrane elementME in the first position.

As has already been mentioned, the actuator element E in the specificexample of FIG. 1 is configured as a shape memory alloy element SMA. Afirst end E1 of the shape memory alloy element SMA herein iselectrically connected to the circuit board LP. At the first fasteningportion BA1, a second end E2, opposite the first end E1, of the shapememory alloy element SMA is connected to the lever element H.

The linking region AB herein is designed such that said linking regionis mechanically connected to a wall of the third valve chamber K3, or ahousing of the pneumatic valve PV (here the cover element DE),respectively, as well as electrically connected to the circuit board LP.

When the shape memory alloy element SMA now is impinged with electricenergy, the shape memory alloy element SMA is heated. On accountthereof, the shape memory alloy element SMA is shortened such that thelever element H rotates about the linking region AB. On account of therotation of the lever element H, the first as well as the secondfastening portion BA1, BA2 are rotated about the linking region AB.Since the second lever arm HA2 is larger than the first lever arm HALthe second fastening portion BA2 is rotated to a greater extent than thefirst fastening portion BA1.

In one embodiment, the coupling element KE can be connected to the leverelement H and the membrane element ME such that, when the shape memoryalloy element SMA is impinged with electric energy, the coupling elementKE moves in the direction toward the cover element AE, thus upward. Onaccount thereof, the membrane element ME by tension so to speak is movedupward until the membrane element ME finally physically contacts thecover element AE and closes the third fluid passage FD3.

By contrast, the coupling element KE in the specific example of FIG. 1is not fixedly connected to the lever element H or to the membraneelement ME but is merely laterally guided. The membrane element ME isfurthermore shaped in such a manner that the membrane element ME haspretensioning to the first position and, on account thereof, closes orseals, respectively, in a self-acting manner the fluid passage FD3. Inthis case, the membrane element ME therefore exerts a compressive forceon the coupling element KE, said compressive force pushing the couplingelement KE upward. Since the shape memory alloy element SMA in this caseis impinged with electric energy anyway and the lever element Hconsequently rotates upward about the linking region AB, the couplingelement KE can be readily moved upward by the compressive force of themembrane element ME. It is any case ensured on account thereof that themembrane element ME in the first position can fluidically close thethird fluid passage FD3.

As can furthermore be seen in FIG. 1 , the first fluid passage FD1, orthe first axis AX1 thereof, respectively, the third fluid passage FD3,or the second axis AX2 thereof, respectively, the cover element AE andthe base element ZE are configured in such a manner that the membraneelement ME in the first position not only closes the third fluid passageFD3 but also releases the first fluid passage FD1. At the same time, thesecond fluid passage FD2 is opened. In the first position of themembrane element ME, a fluidic connection is thus established betweenthe first valve chamber K1 and the fourth valve chamber K4 (via thefirst fluid passage FD1) and between the fourth valve chamber K4 and thesecond valve chamber K2 (via the second fluid passage FD2), withoutthere being a fluidic connection between the first valve chamber K1 andthe third valve chamber K3. The pressurized fluid can therefore onlyflow from the fluid source FQ into the first valve chamber K1 and fromthere via the second valve chamber K2 into the fluid bladder FB.

However, since the third fluid passage FD3 is closed in the firstposition of the membrane element ME, the pressurized fluid cannot flowinto the third valve chamber K3. However, since the actuator element E,or the shape memory alloy element SMA, respectively as well as thecircuit board thereof are disposed in the third valve chamber K3, it isnot necessary for the actuator element E, or the circuit board LPthereof, respectively, to be disposed in a fluid-tight manner in thethird valve chamber K3. This reduces the complexity in terms ofconstruction of the pneumatic valve PV and saves costs when electricallylinking the shape memory alloy element SMA.

Reference is now to be made to FIG. 2 which shows the membrane elementME in the second position. For improved clarity, the vehicle seat FZS,the fluid bladder FB, and the fluid source FQ are not shown in FIG. 2 .

As has already been mentioned, the actuator unit A comprises an actuatorelement E which in the specific case is configured as a shape memoryalloy element SMA, as well as a membrane element ME, a coupling elementKE, and a lever element H.

In order to now be able to move the membrane element ME, proceeding fromits pretensioned position or the first position, to the second position,the actuator unit A furthermore comprises a restoring element RS whichis connected to the housing of the pneumatic valve PV and to the leverelement H, or the second fastening portion BA2, thereof, respectively.The restoring element RS exerts a restoring force on the lever element Hsuch that the lever element H is pretensioned in the direction towardthe base element ZE.

When the impingement of the actuator element E, or of the shape memoryalloy element SMA, respectively, with electric energy is now terminated,the shape memory alloy element SMA reassumes the original shape orlength thereof, respectively. The restoring element RS now moves thelever element H in the direction toward the base element ZE. On accountthereof, the lever element H in turn exerts a compressive force on thecoupling element KE. The restoring element RS is furthermore configuredin such a manner that the compressive force exerted by the lever elementH on the coupling element KE is greater than the compressive forceexerted by the membrane element ME on the coupling element KE.Consequently, the lever element H can push the coupling element KE inthe direction toward the base element ZE until the membrane element MEphysically contacts the base element ZE.

The membrane element ME in this second position now releases the thirdfluid passage FD3 and at the same time closes the first fluid passageFD1.

As can furthermore be readily seen in FIG. 2 , the membrane elementdefines a plurality of passage openings DO1, DO2. Of said plurality ofpassage openings DO1, DO2, at least the passage opening DO1 is disposedin such a manner that a fluidic connection between the second fluidpassage FD2 and the third fluid passage FD3 is established in the secondposition of the membrane element ME. In the second position of themembrane element ME, a fluidic connection is thus established betweenthe second valve chamber K2 and the fourth valve chamber K4 (via thesecond fluid passage FD2) and between the fourth valve chamber K4 andthe third valve chamber K3 (via the third fluid passage FD3), withoutthere being a fluidic connection between the first valve chamber K1 andthe third valve chamber K3. The pressurized fluid can therefore not flowfrom the fluid source FQ into the third valve chamber K3. Nevertheless,the fluid situated in the fluid bladder FB can flow via the second fluidpassage FD2 and the passage opening DO1 into the fourth valve chamber K4and from there via the third fluid passage FD3 into the third valvechamber K3. Since the third valve chamber K3 is also connected to theenvironment, the fluid can flow from the third valve chamber K3 into theenvironment such that the fluid bladder FB can finally be emptied.

Since the third fluid passage FD3 in the second position of the membraneelement ME is opened and at the same time the first fluid passage FD1 isclosed, only the fluid present in the fluid bladder FB can flow into thethird valve chamber K3. Since the fluid of the fluid bladder FB is to befed to the environment anyway, it is in turn not necessary for theactuator element E, or the shape memory alloy element SMA, respectively,and the circuit board LP thereof to be disposed in a fluid-tight mannerin the third valve chamber K3. On account thereof, a cost-effectivepneumatic valve PV which is simple in terms of construction and in whichcomplex seals in the region of the actuator element E can be dispensedwith is achieved.

Since the first axis AX1 of the first fluid passage FD1 and the secondaxis AX2 of the third fluid passage FD3 are moreover disposed so as tobe mutually coaxial, the first and the second position of the membraneelement ME can be implemented by a simple linear upward and downwardmovement of the membrane element ME. Moreover, the coupling element KEis disposed so as to be coaxial with the first and the second axis AX1,AX2, or the coupling element KE in the direction of longitudinal extentextends along an axis which is disposed so as to be coaxial with thefirst and the second axis AX1, AX2, respectively, such that a force ofthe coupling element KE acts centrically on the membrane element ME.This leads to particularly uniform sealing along a circumference of thefirst fluid passage FD1.

Since switching and/or flow noises which under certain circumstances canbe perceived to be annoying can be created when switching the membraneelement ME between the first position and the second position, thepneumatic valve PV can additionally comprise a sound absorption element(not shown) which is disposed on the cover element AE. The soundabsorption element can comprise a sound-absorbent material such as afoam or a felt, and can be soft on the one hand and fluid-permeable onthe other hand, such that a generation of noise when switching themembrane element ME can be substantially damped. The sound absorptionelement can furthermore define a central passage D through which thecoupling element KE extends. This permits particularly efficient noisedamping.

Reference is now to be made to FIG. 3 in which a schematic detailed viewof a fragment of a further embodiment of the pneumatic valve PVaccording to the disclosure is shown. FIG. 3 again shows the membraneelement ME in the first position.

The membrane element ME comprises a first sealing portion DA1 forfluidically sealing the first fluid passage FD1, and a second sealingportion DA2 for fluidically sealing the third fluid passage FD3. Thefirst sealing portion DA1 moreover comprises a first mechanicalreinforcement portion V1, and the second sealing portion DA2 moreovercomprises a second mechanical reinforcement portion V2. The mechanicalreinforcement portions V1, V2 serve for reinforcing in mechanical termsthe membrane element ME in the region of the first and the secondsealing portion DA1, DA2. On account thereof, the membrane element ME inthe region of the first and the second sealing portion DA1, DA2 is morestable in mechanical terms and, on account thereof, the membrane elementME can better and more reliably seal the first and the third fluidpassage FD1, FD3, this increasing the longevity of the membrane elementME. Of course, in other embodiments it is also possible for only thefirst or only the second sealing portion DA1, DA2 to comprise amechanical reinforcement portion of this type. The mechanicalreinforcement portions V1, V2 can be configured, for example, asmaterial thickenings (indicated by the dashed lines) and in theproduction of the membrane element ME can be configured conjointly with,or integrally to, the membrane element ME, respectively. This can beperformed by extruding or injection-molding, for example.

As can furthermore be seen in FIG. 3 , the membrane element MEperipherally comprises a clamping portion ESPA via which the membraneelement ME is clamped between the cover element AE and the base elementZE. The clamping portion ESPA furthermore comprises a materialthickening V3, V4. Like the reinforcement portions V1, V2, the materialthickening V3, V4 can be configured conjointly with, or integrally to,the membrane element ME, respectively, in the production of the membraneelement ME. This can be performed by extruding or injection-molding, forexample.

The material thickening V3, V4 serves to render the membrane element MEin the clamping portion ESPA as reinforced and, on account thereof, morestable in mechanical terms. Moreover, the material thickening V3, V4serves for equalizing production-related dimensional tolerances in theproduction of the cover element AE and of the base element ZE. Onaccount thereof, cavities that can potentially be created in the regionbetween the cover element AE and the base element ZE can be avoided.

As can furthermore be seen in FIG. 3 , the coupling element KE in thespecific case of FIG. 3 is not configured as a separate element but as atappet ST that is molded to the membrane element ME. The tappet STextends from the membrane element ME in the direction toward the coverelement AE, thus in the direction toward the lever element H, or theactuator element E, respectively, and extends through the third fluidpassage FD3. The tappet ST can again be configured conjointly with, orintegrally to, the membrane element ME, respectively, in the productionof the membrane element ME. This can be performed by extruding orinjection-molding, for example.

In that the coupling element KE is configured as a tappet ST on themembrane element ME, it is particularly simple for a coupling betweenthe actuator element E and the membrane element ME to be established.Moreover, since the tappet ST is molded directly to the membrane elementME, an effective transmission of force from the lever element H to themembrane element ME can be performed. It is particularly preferable forthe tappet ST and the mechanical reinforcement portions V1, V2 to beconjointly configured since the tappet ST in this instance comprises asolid base in the form of, for example, the second mechanicalreinforcement portion V2. On account thereof, a particularly positivetransmission of force is possible simultaneously with a minordeformation of the membrane element ME.

Reference is now to be made to FIG. 4 which shows a schematic detailedview of the embodiment of FIG. 3 , wherein the membrane element ME inFIG. 4 is shown in the second position.

As has already been mentioned in the context of FIG. 2 , the membraneelement ME defines a plurality of passage openings DO1, DO2. Saidpassage openings DO1, DO2 serve as pressure equalization between theupper side and the lower side of the membrane element ME. The passageopening DO1 is moreover disposed in such a manner that there is afluidic connection between the second fluid passage FD2 and the thirdfluid passage FD3 in the second position of the membrane element ME, onaccount of which fluid can flow from the fluid bladder FB via the secondvalve chamber K2, the fourth valve chamber K4, and the third valvechamber K3, into the environment. This is schematically illustrated byan arrow in FIG. 4 .

A fluid passage area FDF1 of the passage opening DO1 herein is chosen insuch a manner that said fluid passage area FDF1 is at least as large asa fluid passage area FDF2 of the third fluid passage FD3. The fluidpassage area herein describes the available area through which the fluidcan pass or flow, respectively, through the passage opening DO1 or thethird fluid passage FD3. In the case of the third fluid passage FD3, forexample, the fluid passage area FDF2 is the annular area between anexternal wall of the tappet ST and the wall of the fluid passage FD3.

In that the fluid passage area FDF1 is at least as large as the fluidpassage area FDF2 it is ensured that an ideally minor differentialpressure prevails on the membrane element ME between the lower side(that side that faces the second fluid passage FD2) and the upper side(that side that faces the third fluid passage FD3) of the membraneelement ME. An ideally minor differential pressure is thereforeimportant because a (differential pressure) force that acts on themembrane element ME can be minimized on account thereof. This results inthat the force acting from the membrane element ME via the lever elementH on the actuator element E is also minimized. On account thereof, theactuating force to be provided by the actuator element E is notunnecessarily increased.

Of course, it is also possible for the membrane element ME to define aplurality of passage openings DO1 which establish a fluidic connectionbetween the second valve chamber K2 and the third valve chamber K3. Inthis case, the passage openings are chosen such that an overall fluidpassage area through said plurality of passage openings is at least aslarge as the fluid passage area FDF2 of the third fluid passage FD3.

Reference is now to be made to FIG. 5 which shows a schematic view of afirst valve assembly VBG1. The first valve assembly VBG1 is constructedfrom a first pneumatic valve PV1 and a second pneumatic valve PV2. Thefirst pneumatic valve PV1 and the second pneumatic valve PV2 herein arein principle of identical construction to the pneumatic valve PV whichhas already been described in the context of FIGS. 1 to 4 .

The first pneumatic valve PV1 comprises a first actuator unit A1 whichcomprises a first membrane element ME1, a first coupling element KE1, afirst lever element 111, a first actuator element, and a first restoringelement RS1. The second pneumatic valve PV2 comprises a second actuatorunit A2 which comprises a second membrane element ME2, a second couplingelement KE2, a second lever element 112, a second actuator element, anda second restoring element RS2.

The first actuator element and the second actuator element in thespecific example of FIG. 5 are again configured as shape memory alloyelements SMA1, SMA2. Of course, the first and the second actuatorelements can also be other actuator elements such as piezoelectric ormagnetic actuator elements.

The first valve assembly VBG1 is configured for filling and/or emptyingtwo separated or separate fluid bladders FB1, FB2, respectively. To thisend, the first valve chamber K11 of the first pneumatic valve PV1 isfluidically connected to the first valve chamber K12 of the secondpneumatic valve PV2. The first valve chamber K11 of the first pneumaticvalve PV1 and the first valve chamber K12 of the second pneumatic valvePV2 are in each case connected to the fluid source FQ. In the specificexample of FIG. 5 , the first valve chambers K11, K12 are configured asa common valve chamber which is formed by the basic element BE and thebase element ZE. Furthermore, the second valve chamber K21 of the firstpneumatic valve PV1 is fluidically connected to the first fluid bladderFB1 via a first fluid connector FA11, and the second valve chamber K22of the second pneumatic valve PV2 is fluidically connected to the secondfluid bladder FB2 via a second fluid connector FA12. The third valvechamber K31 of the first pneumatic valve PV1 and the third valve chamberK32 of the second pneumatic valve PV2 are in each case connected to theenvironment. In the specific example of FIG. 5 , the third valvechambers K31, K32 are configured by a common valve chamber which isformed by the base element ZE and the cover element DE.

The first membrane element ME1 in the first valve assembly VBG1 ismovable between a first position and a second position such that eitherthe first valve chamber K11 can be fluidically connected to the secondvalve chamber K21, or the second valve chamber K21 can be fluidicallyconnected to the third valve chamber K31. Likewise, the second membraneelement ME2 in the first valve assembly VBG1 is movable between a firstposition and a second position such that either the first valve chamberK12 can be fluidically connected to the second valve chamber K22, or thesecond valve chamber K22 can be fluidically connected to the third valvechamber K32.

For improved clarity, the first membrane element ME1 and the secondmembrane element ME2 in FIG. 5 are in each case shown in the secondposition. Of course, the first membrane element ME1 and the secondmembrane element ME2 can in each case assume either the first positionor the second position in a mutually independent manner. For example,when the second membrane element ME2 is in the second position as shownin FIG. 5 and the first membrane element ME1 is in the first position,the first fluid bladder FB1 can thus be supplied with a fluid providedby the fluid source FQ while the second fluid bladder FB2 is ventilated.

Depending on the position of the first membrane element ME1 or of thesecond membrane element ME2, respectively, it is thus possible for thefirst and the second fluid bladder FB1, FB2 to be filled and/or emptiedin a mutually separate manner via the first valve assembly VBG1. A3/2-way valve via which two fluid bladders can be filled and/or emptiedin a mutually separate manner is thus achieved in a simple manner bythis design embodiment.

Of course, it is possible for more than two fluid bladders to be filledor to be emptied in a mutually separate manner. To this end, furtherpneumatic valves merely have to be conjointly switched in acorresponding manner with the first pneumatic valve PV1 and the secondpneumatic valve PV2.

Reference is now to be made to FIG. 6 which shows a schematic sectionalview of the first valve assembly VBG1 along the line I-I of FIG. 5 .

As can be seen in FIG. 6 , the valve connectors FA11, FA12 and theactuator units A1, A2 are disposed so as to be mutually offset such thatthe first valve assembly VBG1 is configured so as to be as space-savingas possible.

Reference is now to be made to FIG. 7 which shows a schematic view of asecond valve assembly VBG2. The second valve assembly VBG2 isconstructed from a first pneumatic valve PV3 and a second pneumaticvalve PV4. The first pneumatic valve PV3 and the second pneumatic valvePV4 herein are of a fundamentally identical construction as thepneumatic valve PV which has already been described in the context ofFIGS. 1 to 4 ; however, the first valve chamber of the second pneumaticvalve PV4 here is conjointly switched in a somewhat different manner, aswill be explained in more detail later.

The first pneumatic valve PV3 again comprises a first actuator unit A3which comprises a first membrane element ME3, a first coupling elementKE3, a first lever element 113, a first actuator element, and a firstrestoring element RS3. The second pneumatic valve PV4 comprises a secondactuator unit A4 which comprises a second membrane element ME4, a secondcoupling element KE4, a second lever element 114, a second actuatorelement, and a second restoring element RS4. As opposed to the designembodiment in FIG. 5 , a common leaf spring is used as a commonrestoring element for the first and the second restoring element RS3,RS4 in FIG. 7 .

The first actuator element and the second actuator element in thespecific example of FIG. 7 are again configured as shape memory alloyelements SMA3, SMA4. Of course, the first and the second actuatorelements can also be other actuator elements such as piezoelectric ormagnetic actuator elements.

The second valve assembly VBG2 is configured as a 3/3-way valve forfilling and/or emptying a single fluid bladder FB3 or for maintainingthe pressure in the latter. To this end, the second valve assembly VBG2has three switched positions which are shown in FIGS. 7 to 9 . The firstswitched position by which the fluid bladder FB3 can be filled is shownin FIG. 7 . The second switched position by which the pressure in thefluid bladder FB3 can be maintained is shown in FIG. 8 . The thirdswitched position by which the fluid bladder FB3 can be emptied is shownin FIG. 9 .

As can be seen in FIG. 7 , in the second valve assembly VBG2 the secondvalve chamber K23 of the first pneumatic valve PV3 is fluidicallyconnected to the second valve chamber K24 of the second pneumatic valvePV4. The second valve chambers K23, K24 herein are configured as acommon valve chamber which again is formed by the basic element BE andthe base element ZE. Furthermore, the first valve chamber K13 of thefirst pneumatic valve PV3 is fluidically connected to the fluid sourceFQ via a first fluid connector FA13, and the first valve chamber K14 ofthe second pneumatic valve PV4 is fluidically connected to the fluidbladder FB3 via a second fluid connector FA14. In the case of the secondpneumatic valve PV4, the first valve chamber K14 is thus not connectedto a fluid source (as in the case of the first valve assembly VBG1, cf.FIG. 5 ) but to the fluid bladder FB3. The third valve chamber K33 ofthe first pneumatic valve PV3 and the third valve chamber K34 of thesecond pneumatic valve PV4 are again in each case connected to theenvironment. In the specific example of FIG. 7 , the third valvechambers K33, K34 are again configured as a common valve chamber whichis formed by the base element ZE and the cover element DE.

As in the first valve assembly VBG1, the first membrane element ME3 inthe second valve assembly VBG2 is also movable between a first positionand a second position such that either the first valve chamber K13 canbe fluidically connected to the second valve chamber K23, or the secondvalve chamber K23 can be fluidically connected to the third valvechamber K33. Likewise, the second membrane element ME4 in the secondvalve assembly VBG2 is movable between a first position and a secondposition such that either the first valve chamber K14 can be fluidicallyconnected to the second valve chamber K24, or the second valve chamberK24 can be fluidically connected to the third valve chamber K34.

When the fluid bladder FB3 is now to be filled, the first shape memoryalloy element SMA3 and the second shape memory alloy element SMA4 are ineach case impinged with electric energy such that the first membraneelement ME3 as well as the second membrane element ME4 move to thesecond position. On account thereof, a fluidic connection is establishedbetween the fluid source FQ, the first valve chamber K13, the two secondvalve chambers K23, K24, and the first valve chamber K14. On accountthereof, fluid from the fluid source FQ can flow into the fluid bladderFB3, and the fluid bladder FB3 can be filled.

When the pressure in the fluid bladder FB3 is now to be maintained (cf.FIG. 8 ), an impingement of the first and of the second shape memoryalloy element SMA3, SMA4 with energy is thus terminated. The first andthe second membrane element ME3, ME4 by virtue of the restoring force ofthe leaf springs (the first and the second restoring element RS3, RS4)move to the second position. On account thereof, a fluidic connectionbetween the fluid source FQ and the second valve chamber K23 of thepneumatic valve PV3 is interrupted. Likewise, a fluidic connectionbetween the fluid bladder FB3 and the second valve chamber K24 of thesecond pneumatic valve PV4 is interrupted. Fluid can thus neither flowfrom the fluid source FQ into the fluid bladder FB3, nor can fluid flowfrom the fluid bladder FB3 into the environment. The pressure in thefluid bladder FB3 is thus maintained. Moreover, no fluid can flow fromthe fluid source FQ to the fluid bladder FB3 even in the event of aleakage of the presently sealed fluid passages FD13 and/or FD14, sincethe fluid would be discharged via the fourth valve chambers K43 and K44,respectively, which are connected to the environment. Unintentionalfilling of the fluid bladder FB3 is thus reliably avoided in thepressure-maintaining state without any impingement of the first and ofthe second shape memory alloy element SMA3, SMA4 with energy.

When the fluid bladder FB3 now is to be emptied or ventilated,respectively, (cf. FIG. 9 ), only the second shape memory alloy elementSMA4 is impinged with electric energy. Then, the second membrane elementME4 again moves to the first position such that there is a fluidicconnection between the fluid bladder FB3, the first valve chamber K14,and the second valve chambers K23, K24. Since the first membrane elementME3 is furthermore in the second position, there is a fluidic connectionbetween the second valve chambers K23, K24 and the third valve chamberK33 (and also K34, respectively). On account thereof, there is in turn afluidic connection between the fluid bladder FB3 and the environmentsuch that fluid present in the fluid bladder FB3 can flow from the fluidbladder FB3 into the environment, and the fluid bladder FB3 can beventilated or emptied.

Of course, in order to save installation space, the actuator units A3,A4 can be disposed so as to be mutually offset, in a manner similar tothe first valve assembly VBG1 (cf. FIG. 6 ).

The second valve assembly VBG2 represents a 3-3-way NC valve for fillingand/or emptying a fluid bladder FB3 and for maintaining pressure in thelatter, wherein it is not necessary for the actuator elements to bedisposed in a fluid-tight manner in the valve. The second valve assemblyVBG2 enables in particular the implementation of a massage functionwithout the risk of unintentionally filling the fluid bladder FB3.

While the activation of the membrane element in the context of FIGS. 1and 9 has been described in such a manner that the membrane element whenterminating the impingement with electric energy is in the secondposition, it is of course also possible for the operating mode of theactuator unit to be varied such that the membrane element whenterminating the impingement with electric energy is in the firstposition. On account thereof, an NC valve or an NO valve can beachieved, depending on the specific application.

While the membrane element in the context of FIGS. 1 to 9 has beendescribed in such a manner that said membrane element is pretensioned tothe first position, it is of course also possible for the membraneelement to be shaped in such a manner that said membrane element ispretensioned to the second position. In this case, merely the operatingmode of the actuator unit and optionally the operating mode of therestoring element as well as the coupling element have to be modified ina corresponding manner.

The invention claimed is:
 1. A pneumatic valve for a fluid bladder of apneumatic seat adjustment device of a vehicle seat, comprising: a firstvalve chamber configured to be connected to a fluid source; a secondvalve chamber separate from the first valve chamber and configured to beconnected to the fluid bladder; a third valve chamber separate from thefirst valve chamber and the second valve chamber and configured to beconnected to an environment of the pneumatic valve; a fourth valvechamber separate from the first valve chamber, the second valve chamberand the third valve chamber and fluidically connected to the first valvechamber via a first fluid passage, fluidically connected to the secondvalve chamber via a second fluid passage and fluidically connected tothe third valve chamber via a third fluid passage; and an actuator unitcomprising a membrane element disposed in the fourth valve chamber andan actuator element disposed in the third valve chamber, wherein theactuator element is coupled to the membrane element and configured tomove the membrane element between a first position in which the firstfluid passage is opened and the third fluid passage is closed, and asecond position in which the first fluid passage is closed and the thirdfluid passage is opened.
 2. The pneumatic valve as claimed in claim 1,wherein the actuator element is a shape memory alloy element configuredto activate the membrane element when impinged with electric energy. 3.The pneumatic valve as claimed in claim 1, wherein the membrane elementcomprises a first sealing portion for fluidically sealing the firstfluid passage and a second sealing portion for fluidically sealing thethird fluid passage, and wherein the membrane element in a region of atleast one of the first sealing portion and the second sealing portioncomprises a mechanical reinforcement portion for reinforcing themembrane element in mechanical terms.
 4. The pneumatic valve as claimedin claim 1, wherein the membrane element defines a passage opening whichin the second position of the membrane element is configured tofluidically connect the third fluid passage to the second fluid passage.5. The pneumatic valve as claimed in claim 4, wherein a fluid passagearea of the passage opening is at least as large as a fluid passage areaof the third fluid passage.
 6. The pneumatic valve as claimed in claim1, wherein the actuator unit comprises a coupling element which couplesthe membrane element to the actuator element.
 7. The pneumatic valve asclaimed in claim 6, wherein the coupling element extends through thethird fluid passage.
 8. The pneumatic valve as claimed in claim 6,wherein the coupling element is a tappet molded to the membrane elementand extends from the membrane element in a direction toward the actuatorelement.
 9. The pneumatic valve as claimed in claim 1, wherein themembrane element is shaped so that the membrane element is pretensionedto at least one of the first position and the second position.
 10. Thepneumatic valve as claimed in claim 1, wherein the fourth valve chamberis defined by a pot-shaped base element and a cover element that coversthe base element, and the membrane element comprises a clamping portionwhich is configured to clamp the membrane element between the baseelement and the cover element.
 11. The pneumatic valve as claimed inclaim 10, wherein the clamping portion comprises a material thickeningconfigured to at least one of reinforce the membrane element inmechanical terms and equalize tolerances between the base element andthe cover element.
 12. The pneumatic valve as claimed in claim 1,wherein the actuator unit further comprises a lever element disposed inthe third valve chamber and movably connected to a housing of thepneumatic valve via a linking region, wherein a first fastening portionof the lever element is connected to the actuator element and a secondfastening portion of the lever element is connected to a couplingelement so that when activating the actuator element a movement of thelever element is converted to a movement of the coupling element. 13.The pneumatic valve as claimed in claim 12, wherein the actuator elementis fastened to the first fastening portion so that a first lever arm isformed between the first fastening portion and the linking region, andthe coupling element is fastened to the second fastening portion so thata second lever arm which is larger than the first lever arm is formedbetween the second fastening portion and the linking region.
 14. A valveassembly for two fluid bladders of an adjustment device of a vehicleseat, comprising: a first pneumatic valve as claimed in claim 1configured to at least one of fill and empty a first fluid bladder; anda second pneumatic valve as claimed in claim 1, which is configured toat least one of fill and empty a second fluid bladder, wherein: thefirst valve chamber of the first pneumatic valve is fluidicallyconnected to the first valve chamber of the second pneumatic valve; atleast one of the first valve chamber of the first pneumatic valve andthe first valve chamber of the second pneumatic valve is configured tobe fluidically connected to the fluid source; the second valve chamberof the first pneumatic valve is configured to be connected to the firstfluid bladder; the second valve chamber of the second pneumatic valve isconfigured to be connected to the second fluid bladder; and the thirdvalve chamber of the first pneumatic valve and the third valve chamberof the second pneumatic valve are configured to be connected to theenvironment.
 15. A valve assembly for a fluid bladder of an adjustmentdevice of a vehicle seat, comprising: a first pneumatic valve as claimedin claim 1; and a second pneumatic valve as claimed in claim 1, wherein:the second valve chamber of the first pneumatic valve is fluidicallyconnected to the second valve chamber of the second pneumatic valve; thefirst valve chamber of the first pneumatic valve is configured to beconnected to the fluid source; the first valve chamber of the secondpneumatic valve is configured to be connected to the fluid bladder; andthe third valve chamber of the first pneumatic valve and the third valvechamber of the second pneumatic valve are configured to be connected tothe environment.
 16. An adjustment device for adjusting a contour of aseat bearing surface of a vehicle seat, comprising: a fluid bladder foradjusting the contour of the seat bearing surface; and a pneumatic valveas claimed in claim 1, the second valve chamber of said pneumatic valvebeing fluidically connected to the fluid bladder.